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United States Department of Agriculture

Agricultural Research Service

Areawide Fire Ant Project
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                        2008 Annual Areawide Fire Ant Report.

 

FINAL REPORT   

Areawide Suppression of Fire Ants: Demonstration Project in Mississippi

 

 

 

 

D.A. Streett1, A.M. Pranschke1, J.T. Vogt1, Jack T. Reed2, and Anne-Marie Callcott3  

 1USDA, ARS, Biological Control of Pests Research Unit

59 Lee Rd. Stoneville, MS 38776

2Department of Entomology and Plant Pathology,

Mississippi State University, Mississippi State, MS 39762

3USDA, APHIS, PPQ, CPHST

3505 25th Ave. Bldg. 16 Gulfport, MS 39501

INTRODUCTION

The USDA-ARS demonstration project for the suppression of imported fire ants has entered its seventh year. In 2005, Mississippi State University joined the project monitoring sites in Clay and Grenada Counties and incorporating two additional sites, located in Oktibbeha County. In 2006, two more sites were added, one in Lowndes County and one in Chickasaw County.

The Areawide   project integrates biological   control   agents    with    the chemical   bait   products hydramethylnon  and methoprene.  Mississippi’s involvement in the project has focused on black/ hybrid imported fire ants (Fig. 1).  The following is a report on the status of the USDA-ARS Areawide Suppression of    Fire   Ants    Demonstration   Project   in   Mississippi as of 2006.

 

METHODS

Our study was conducted at four sites, 2 sites located in Grenada County, MS received a chemical bait treatment only, and 2 sites located in Clay county, MS that received both a chemical bait treatment and biological control agents (Fig. 1).  Treatment areas consisted of at least 220 acres with a 280 acre minimum untreated contiguous border. Fifty circular plots (0.25 acre each) were established at each of our four sites: 20 plots in the treatment and 30 plots in the boundary. Treatment and boundary plots were monitored 4 times/year and 2 times/year, respectively. Mound counts and hotdog bait attractants were conducted every sampling period with pitfall samples collected only in the spring and fall.

 

Figure 1. Distribution of imported fire ants in Mississippi.  Areawide sites are located in shaded counties.

 

 

Chemical Treatment Only:

Site 1.  Woodland Plantation, Holcomb, MS, Grenada Co.

 MS County Extension Agent- Mr. Steve Winters

Chemically-treated acreage: 253 acres

Peripheral acreage: 1585 acres

                       

Woodland Plantation is located approx. 80 miles northeast of Stoneville, outside the flat lands of the Mississippi Delta. The site was found in the fall of 2001. At that time, vial samples from 100 mounds were collected and inspected for the presence of Thelohania sp. Presence of the disease was not detected. Furthermore, inspections for the presence of the phorid fly were negative. Plots were established and pretreatment data were collected at the end of April and early May 2002.  Aerial applications of the combined chemical baits Siege Pro and Extinquish were applied June 3, 2002 in a cooperative effort between USDA-APHIS, Gulfport, MS and the USDA-ARS in Stoneville. MS.

 

 Figure 2. Linear graph showing the average mounds per acre throughout the study period. Each yellow line    with airplane represents an aerial bait application (application of methoprene and hydromethelnon; 0.75 lbs/acre total). The blue line represents the boundary area (Control) of the site and does not receive bait applications. The pink line represents the area (Treatment) of the site and does receive the aerial bait application. Each marker along the blue or pink lines is a sample date.  Dotted lines (blue and pink) denote periods of time with missing data and therefore may not represent actual field conditions.   

 

                                                                                                   

 

 

Figure 3. Digital OrthoQuadrangle photo of Woodland Plantation, Grenada County, with a GPS marked treatment area and numbered ¼ acre plots. Plots not to scale.

 

 

 

An initial survey of the imported fire ant mounds was conducted prior to the initiation of the demonstration project. We analyzed 50 ant samples, by identifying chemicals found on their exoskeleton, to determine what species of fire ants are located at Woodland.

                        Black Imported Fire Ants                                 8%

                        Red Imported Fire Ants                                    2%

                        Hybrid Imported Fire Ants                                90%

(Hybrids are a cross between red and black imported fire ants)

Figure 2 shows a reduction in the average mounds per acre in the area treated with the fire ant bait. Figure 3 shows the area that was treated. In the spring of 2002, Woodland averaged 55 to 75 mounds per acre.  Notice the declines in the pink line after each aerial application (yellow line). This is an indicator that the ants are actively searching and consuming the bait.

Site 2.  Kirkman Place, Near Torrance Landing, Grenada, MS, Grenada Co.

MS County Extension Agent- Mr. Steve Winters

Chemically-treated acreage: 228 acres

Peripheral acreage: 384 acres

 

Kirkman Place is located approx. 95 miles northeast of Stoneville, outside the flat lands of the Mississippi Delta. The site was found in the fall of 2001. At that time, vial samples from 100 mounds were collected and microscopically examined for the presence of Thelohania sp. Presence of the disease was not detected. Furthermore, inspections for the presence of the phorid fly were negative. Plots were established and pretreatment data were collected in May 2002.  An aerial application of the chemical baits was applied June 3, 2002.

Figure 4. Linear graph showing the average mounds per acre throughout the study period. Each yellow line with airplane represents an aerial bait application (application of methoprene and hydromethelnon; 0.75 lbs/acre total). The blue line represents the boundary area (Control) of the site and does not receive bait applications. The pink line represents the area (Treatment) of the site and does receive the aerial bait application. Each marker along the blue or pink lines is a sample date.  Dotted lines (blue and pink) denote periods of time with missing data and therefore may not represent actual field conditions.

 

 

Figure 5. Digital OrthoQuadrangle photo of Torrance (Kirkman Place), Grenada County, with a GPS marked treatment area and numbered ¼ acre plots. Plots not to scale.

 

 

 

An initial survey of the imported fire ant mounds was conducted prior to the initiation of the demonstration project. We analyzed 50 ant samples, by identifying chemicals found on their exoskeleton, to determine what species of fire ants are located at Torrance.

 

                        Black Imported Fire Ants                                 24%

                        Red Imported Fire Ants                                    2%

                        Hybrid Imported Fire Ants                                74%

(Hybrids are a cross between red and black imported fire ants)

 

     Figure 4 shows a reduction in the average mounds per acre in the area treated with the fire ant bait. Figure 5 shows the area that was treated. In the spring of 2002, Torrance averaged 40 to 50 mounds per acre.  Notice the declines in the pink line after each aerial application (yellow line). This is an indicator that the ants are actively searching and consuming the bait.

 

     Chemical and Biological Control:

 

Site 3. Knox Farms, West Point, MS, Clay Co.

MS County Extension Agent- Mr. Perry Kimbrough

Chemically-treated acreage: 253 acres

Peripheral acreage: 319 acres

 

Knox Farms is located approx. 150 miles east of Stoneville. The site was found in the fall of 2001. At that time, vial samples from 100 mounds were collected and inspected for the presence of Thelohania sp. Presence of the disease was not detected. Furthermore, inspections for the presence of the phorid fly were negative. Plots were established and pretreatment data were collected in May 2002.  An aerial application of the chemical baits was applied June 4, 2002.

 

Figure 6. Linear graph showing the average mounds per acre throughout the study period. Each yellow line with airplane represents an aerial bait application (application of methoprene and hydromethelnon; 0.75 lbs/acre total). The blue line represents the boundary area (Control) of the site and does not receive bait applications. The pink line represents the area (Treatment) of the site and does receive the aerial bait application. Each marker along the blue or pink lines is a sample date.  Dotted lines (blue and pink) denote periods of time with missing data and therefore may not represent actual field conditions.

 

 

 

 

Figure 7. Digital OrthoQuadrangle photo of Knox Farms, Clay County, with a GPS marked treatment area and numbered ¼ acre plots. Plots not to scale.

 

 

An initial survey of the imported fire ant mounds was conducted prior to the initiation of the demonstration project. We analyzed 50 ant samples, by identifying chemicals found on their exoskeleton, to determine what species of fire ants are located at Knox.

 

                        Black Imported Fire Ants                                 86%

                        Hybrid Imported Fire Ants                                14%

(Hybrids are a cross between red and black imported fire ants)

 

     Figure 6 shows a reduction in the average mounds per acre in the area treated with the fire ant bait. Figure 7 shows the area that was treated. In the spring of 2002, Knox averaged 50 to 60 mounds per acre.  Notice the declines in the pink line after each aerial application (yellow line). This is an indicator that the ants are actively searching and consuming the bait

Site 4. Prima Farms, West Point, MS, Clay County

MS County Extension Agent- Mr. Perry Kimbrough

Chemically-treated acreage: 261 acres

Peripheral acreage: 284 acres

 

Prima Farms is located approx. 150 miles east of Stoneville, just a few miles east of Knox Farms. The site was found in the fall of 2001. At that time, vial samples from 100 mounds were collected and inspected for the presence of Thelohania sp. Presence of the disease was not detected. Furthermore, inspections for the presence of the phorid fly were negative. Plots were established and pretreatment data were collected in May 2002.  Aerial applications of the chemical baits were applied June 4, 2002.

 

 

Figure 8. Linear graph showing the average mounds per acre throughout the study period. Each yellow line with airplane represents an aerial bait application (application of methoprene and hydromethelnon; 0.75 lbs/acre total). The blue line represents the boundary area (Control) of the site and does not receive bait applications. The pink line represents the area (Treatment) of the site and does receive the aerial bait application. Each marker along the blue or pink lines is a sample date.  Dotted lines (blue and pink) denote periods of time with missing data and therefore may not represent actual field conditions.

 

 

 

 

Figure 9. Digital OrthoQuadrangle photo of Prima Farms, Clay County, with a GPS marked treatment area and numbered ¼ acre plots. Plots not to scale.

 

 

 

An initial survey of the imported fire ant mounds was conducted prior to the initiation of the demonstration project. We analyzed 50 ant samples, by identifying chemicals found on their exoskeleton, to determine what species of fire ants are located at Prima.

 

                        Black Imported Fire Ants                                 57%

                        Hybrid Imported Fire Ants                                43%

(Hybrids are a cross between red and black imported fire ants)

 

Figure 8 shows a reduction in the average mounds per acre in the area treated with the fire ant bait. Figure 9 shows the area that was treated. In the spring of 2002, Prima averaged 30 to 40 mounds per acre.  Notice the declines in the pink line after each aerial application (yellow line). This is an indicator that the ants are actively searching and consuming the bait. However, the 2004 fall application did not effectively reduce ant mounds (notice the pink line rise). This may be due to the application being applied immediately after a fog advisory while the ground was still wet, rendering the bait undesirable to the ants. Most of the treatment applications were successful in reducing mounds (notice the pink line consistently below the blue). After the first bait application, fall sampling in 2002 showed a surge in newly formed colonies. Many of these mounds were smaller than a baseball with less than 1000 individuals (large colonies may have as many as 250,000). There also appears to be a declining trend in the control (blue line).  This area surrounding the treatment did not receive any bait.  The pattern follows in all study sites and, therefore, indicates an environmental influence.    

 

IMPACT

Bait Application Treatments

The trigger in Mississippi was set at 20% mound reinfestation. In the fall of 2002, mound densities in both counties exceeded the trigger level.  The Mississippi Spring sampling was completed in early May, 2003 and aerial application of the chemical bait by USDA/APHIS and USDA/ARS personnel followed the 2003 spring sampling.  At four weeks post- application the mound densities were below the trigger level in both counties. At twelve weeks post application, in mid-August the mound densities at the sites in Clay County had reached 23% of the spring mound density.  A 2004 spring bait application for Clay County (biocontrol) was delayed several times and cancelled due to weather. Grenada County did not require treatment because of a 2003 fall application. In fall 2004, mound densities at both counties exceeded the trigger level. Application of chemical bait was applied to both counties mid-October (Grenada on the 13th and Clay on the 18th) after several days of fog delays.

Suppression of the imported fire ants lasted at least four to ten weeks after bait applications, averaging less than ten mounds per acre (Figs. 2, 4, 6, 8).  Mound numbers generally increased by the fall of each year (rise in the pink line indicates more mounds/acre). After the first bait application, fall sampling in 2002 showed a surge in newly formed colonies. Many of these mounds were smaller than a baseball with less than 1000 individuals (large colonies may have as many as 250,000). There also appears to be a declining trend in the control (blue line).  The area surrounding the treatment did not receive any bait; therefore, this pattern follows in all study sites and indicates an environmental influence. 

Phorid fly Releases

The phorid fly rearing program and phorid field release study were conducted by Dr. J. T. Vogt with the USDA-ARS-BCPRU.  The initial phorid fly release was completed in May 2002 at the Knox site in Clay County.  Extensive monitoring on July 11 and 12, 2002 revealed phorid flies in and around the release site with a range of approx. 500 meters from the original release site.  Over wintering was confirmed in May, 2003 and the flies were found approx. 2 kilometers from the release site.  The initial phorid fly release at the Prima site was conducted in August, 2002.  No flies were recovered in May, 2003 from the release site.  An additional release was initiated in June, 2003 and flies were recovered in August, 2003, confirming establishment at both treatment sites.

The fire ant decapitating fly, P. curvatus was first released in two pastures in Clay Co., Mississippi during the spring of 2002 and 2003.  P. curvatus has become established on black and hybrid imported fire ants, Solenopsis richteri and S. invicta X richteri, respectively (Vogt and Streett, 2003).  P. curvatus, as of September 2004, has dispersed to occupy an ellipsoidal area over 2249 km2, or over 224,914 ha.  Average dispersal was 14.5 km/year with a range of 5.5 - 22 km/year.  During mound sampling, time to first fly appearance ranged from about 10 seconds to 20 minutes.

By mid 2006, phorid fly dispersal had expanded over three million acres in Mississippi (Figure 10). Flies have been captured as far west as Holcomb, MS. We first sampled the flies at Woodland on 14 June 2006.   A mound was disturbed by the fence-line near plots 47 and 48 (Figure 2). Approximately eight to ten flies arrived at the mound within 15 minutes.  Compared to the release sites in Clay County, this is a similar number of flies responding to a disturbed mound. To date, no phorid flies have been found at Torrance, the other Grenada site.

 

In 2004 P. litoralis was released at Knox Farms in Clay County, Mississippi. P. litoralis was not found after 11 survey days in the fall of 2004 and four survey days in the spring of 2005. No additional releases of phorid flies were made in 2005 or 2006. 

 

Figure 10. Distribution of phorid flies, Pseudacteon curvatus, in Mississippi since released at Prima Farms, Clay County, in 2003.

 

Thelohania

Imported fire ant colonies were collected from a field site located near Gainesville, FL with a high prevalence of Thelohania solenopsae.  The colonies were examined microscopically to determine disease prevalence.  Our results showed 68% of the colonies infected with T. solenopsae.   Infected brood were collected from the infected colonies and distributed to BIFA mounds during the week of 8 July 2002.  A total of   32 mounds were each inoculated with 3 g of Thelohania-infected brood in the boundary area.  Sufficient infected brood was not available to inoculate the 160 mounds described in the protocol. 

Since July 2002, three attempts have been made to introduce T. solenopsae into two pasture sites in Clay County, Mississippi. In 2002, 82 mounds were each initially challenged with three gms of red imported fire ant brood inoculum. In April 2003, 186 mounds were provided Thelohania-infected brood following the project protocol. Follow-up sampling of the inoculated mounds in the fall of each year failed to yield active infected colonies.

Members of the demonstration project in Florida traveled to Mississippi in April 2004 and administered infected brood to 275 nests between both sites at 5, 8, and 25* grams per nest (*only provided to 2 active mounds). In the fall of 2004, a single mound was recovered at Knox where the individuals were discovered to contain Thelohania spores. The mound was originally challenged with eight gm of infected brood in April 2004.

No inoculation attempts of the fire ant disease, T. solenopsae, were made in Grenada County. The disease was introduced to 543 colonies in Clay County from 2002 to 2004. A single mound was recovered at Knox where the individuals were discovered to contain Thelohania spores. Unfortunately, we were unable to establish the fire ant disease. Follow-up sampling of all active mounds located in our plots, in May 2005, did not yield any other infected colonies.  No inoculation attempts were made in 2005 or 2006.

Pitfall and Bait Attractants

In addition to fire ants, eleven ant species were collected at the demonstration project treatment sites in Mississippi. Two of these species, S. molesta and M. minimum were found on bait samples located in plots with fire ants (Table 1). A total of 12 ant species have been identified at the project sites (Table 1). Forelius pruinosus (Roger) was the only additional species collected in the baits at Prima in spring 2003.

 

Table 1. List of ant species captured at each of the areawide study sites. Names with asterisk (*) were only captured in pitfall traps.

 

 

 

Publications:

Streett, D. A., Vogt, J. T., and Pereira, R. M.  2002. Area-wide suppression of the black imported fire ants on pastures in Mississippi.  Proc. Imported Fire Ant Conf. March 24-26. Athens, GA. p. 138-141.

Streett, D. A., A.M. Pranschke, and Ann-Marie Callcott. 2005. Areawide Suppression of Imported Fire Ants: Demonstration Project in Mississippi, 2004. Proc. Imported Fire Ant Conference, pp. 177-180.

Thead, L. G., J. T. Vogt, and D. A. Streett. 2004. Dispersal of the Fire Ant Decapitating Fly, Pseudacteon curvatus (Diptera:Phoridae) in Northeast Mississippi. Florida Entomologist. v. 88. pp. 214-216.

Vogt, J. T., and Streett, D. A.  2003. Establishment of Pseudacteon curvatus Borgmeier in Mississippi, In Proc. of the 2003 Imported Fire Ant Conference.  p. 58

Vogt, J. T. and Streett, D. A.  2003. Establishment of the decapitating fly Pseudacteon curvatus (Diptera: Phoridae) in Mississippi.   J.  Entomol. Sci. 38(2). 317-320.

Vogt, J. T., Streett, D. A., Pereira, R. M., and Callcott, A. M. A.  2003. Mississippi Areawide Program: Unique Aspects of Working with Black and Hybrid Imported Fire Ants,  Proc. of the 2003 Imported Fire Ant Conference.  p. 59

Vogt, J. T., D. A. Streett, R. M. Pereira and A. M. A. Callcott.  2003. Mississippi areawide fire ant suppression program: Unique aspects of working with black and hybrid imported fire ants.    Journal of Agricultural and Urban Entomology. v. 20 pp. 105-111.

 

Vogt, J. T., D. A. Streett and D. Boykin.  2004. Seasonal characteristics of black imported fire ant (Hymenoptera: Formicidae) mounds in northern Mississippi pastures.    Sociobiology. v. 43 pp. 513-522.

 


Last Modified: 9/9/2008
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